Temperature calibration with band gap absorption method

ABSTRACT

A method and apparatus for calibration non-contact temperature sensors within a process chamber are described herein. The calibration of the non-contact temperature sensors includes the utilization of a band edge detector to determine the band edge absorption wavelength of a substrate. The band edge detector is configured to measure the intensity of a range of wavelengths and determines the actual temperature of a substrate based off the band edge absorption wavelength and the material of the substrate. The calibration method is automated and does not require human intervention or disassembly of a process chamber for each calibration.

FIELD

Embodiments of the present disclosure generally relate to apparatus andmethods for semiconductor processing. More particularly, the apparatusand methods disclosed relate to the calibration of temperature sensorswithin a thermal process chamber.

DESCRIPTION OF THE RELATED ART

Semiconductor substrates are processed for a wide variety ofapplications, including the fabrication of integrated devices andmicrodevices. During processing, the substrate is positioned on asusceptor within a process chamber. The susceptor is supported by asupport shaft, which is rotatable about a central axis. Precise controlover a heating source, such as a plurality of heating lamps disposedbelow and above the substrate, allows the substrate to be heated withinvery strict tolerances. The temperature of the substrate can affect theuniformity of the material deposited on the substrate.

The temperature of the substrate is measured throughout the depositionprocess using non-contact temperature sensors. The non-contacttemperature sensors are disposed on/through a lid of the thermal processchamber. Over time, the temperature readings of the non-contacttemperature sensors drifts due to changes of the conditions of thehardware within the process chamber. Aging of the heating lamps, windowcoatings, and susceptor affect the temperature measurements over time.Previous calibration methods have used calibration kits which utilizeopening of the process chamber and significant down time.

Therefore, a need exists for improved methods and apparatus forcalibrating non-contact temperature sensors within thermal processchambers.

SUMMARY

The present disclosure generally relates to apparatus and methods forcalibrating pyrometers within an epitaxial deposition chamber. Morespecifically, the present disclosure relates to the use of band gap edgedetectors to determine the temperature of a substrate. A measurementassembly for calibrating pyrometers within a processing chamberaccording to one embodiment of the present disclosure includes a bandedge calibration assembly. The band edge calibration assembly includes alight source positioned to emit a light and a band edge detectordisposed adjacent to the light source and positioned to receive thelight emitted by the light source. The measurement assembly forcalibrating pyrometers within a processing chamber further includes afirst pyrometer disposed adjacent to the band edge calibration assemblyand positioned to receive a radiation measurement, and a controllerconnected to each of the light source, the band edge detector, and thefirst pyrometer. The controller is configured to determine a band edgeabsorption wavelength from the light received by the band edge detector.

In another embodiment, the an apparatus for substrate processingincludes a chamber body, a substrate support disposed within the chamberbody, a first transmission member disposed over the substrate supportand within the chamber body, a second transmission member disposed belowthe substrate support and within the chamber body, a lid disposed abovethe first transmission member, a plurality of lamps disposed between thefirst transmission member and the lid, a calibration substrate disposedon the substrate support, a radiation source positioned to directradiation onto or through the calibration substrate; and a band edgecalibration assembly disposed on the lid. The band edge calibrationassembly includes a band edge detector positioned to receive theradiation from the radiation source after being reflected off of orpassing through the calibration substrate. The apparatus for substrateprocessing further includes a first pyrometer is disposed adjacent tothe band edge calibration assembly, and a controller. The controller isconfigured to irradiate a portion of the calibration substrate using theradiation source, measure a band edge absorption wavelength, measure afirst temperature of the calibration substrate using the firstpyrometer, determine an actual temperature of the calibration substrateusing the band edge absorption wavelength, and calibrate the firstpyrometer by comparing the first temperature of the calibrationsubstrate and the actual temperature of the calibration substrate.

In yet another embodiment, a method of calibrating a pyrometer within aprocess chamber is disclosed. The method of calibrating the pyrometerincludes transferring a calibration substrate onto a substrate supportwithin a chamber body, irradiating a portion of the calibrationsubstrate using a light source, measuring a band edge absorptionwavelength using a band edge detector, measuring a first temperature ofthe calibration substrate using a first pyrometer, and determining anactual temperature of the calibration substrate using the band edgeabsorption wavelength. The first pyrometer is calibrated by comparingthe first temperature of the calibration substrate and the actualtemperature of the calibration substrate. The calibration substrate isthen transferred out of the chamber body.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlyexemplary embodiments and are therefore not to be considered limiting ofscope, as the disclosure may admit to other equally effectiveembodiments.

FIG. 1 is a schematic plan view of a substrate processing system,according to one embodiment.

FIG. 2 is a schematic sectional view of a process chamber, according toone embodiment.

FIG. 3 is a schematic side view of a cassette used within a load lockchamber of the substrate processing system of FIG. 1, according to oneembodiment.

FIG. 4 is a schematic sectional view of the measurement assembly usedwithin the process chamber of FIG. 2, according to one embodiment.

FIG. 5 is a method of utilizing the measurement assembly within theprocess chamber of FIG. 2, according to one embodiment.

FIG. 6 is a method of calibrating non-contact temperature sensors withinthe process chamber of FIG. 2, according to one embodiment.

FIG. 7 is a graph illustrating absorption wavelength detection,according to one embodiment.

FIG. 8 is a graph illustrating the correlation between absorptionwavelength and temperature, according to one embodiment.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to apparatus andmethods for semiconductor processing, more particularly, to a thermalprocess chamber. The thermal process chamber includes a substratesupport, a first plurality of heating elements disposed over thesubstrate support, and a measurement assembly disposed within thethermal process chamber to calibrate non-contact temperature sensors.The calibration apparatus and method utilizes a band edge detector todetermine the actual temperature of a calibration substrate. Thecalibration substrate has a known band gap over a range of temperatures.Absorption edge frequency is only dependent upon the material band gapof the calibration substrate and therefore is not affected by changeswithin the hardware of a process chamber, such as the aging of heatlamps, window coatings, or susceptor. The measurement of the band gap ofthe calibration substrate is correlated to a temperature measurement andused to calibrate non-contact temperature sensors, such as pyrometers,within the process chamber.

Using the methods described herein, the non-contact temperature sensorsis calibrated using an automatic process, which does not use humanintervention or the removal of chamber components. The automation of thecalibration process reduces downtime, reduces human error, and improvesthe consistency of the calibration.

A “substrate” or “substrate surface,” as described herein, generallyrefers to any substrate surface upon which processing is performed.Processing includes deposition, etching, and other methods utilizedduring semiconductor processing. For example, a substrate surface whichmay be processed includes silicon, silicon oxide, doped silicon, silicongermanium, germanium, gallium arsenide, glass, sapphire, and any othermaterials, such as metals, metal nitrides, metal alloys, and otherconductive or semi-conductive materials, depending on the application. Asubstrate or substrate surface which may be processed also includesdielectric materials such as silicon dioxide, silicon nitride,organosilicates, and carbon dopes silicon oxide or nitride materials.The substrate itself is not limited to any particular size or shape.Although the embodiments described herein are made with generally madewith reference to a round 200 mm or 300 mm substrate, other shapes, suchas polygonal, squared, rectangular, curved, or otherwise non-circularworkpieces may be utilized according to the embodiments describedherein.

FIG. 1 is a schematic plan view of a substrate processing system 100which includes the process chamber 130 a-d described herein, accordingto one embodiment. The substrate processing system 100 is used toprocess semiconductor substrates by performing a variety of processes onthe substrates. The substrate processing system 100 described hereinincludes a transfer chamber 110, a plurality of process chambers 130a-130 d, load lock chambers 120 a, 120 b, a factory interface (FI) 140,and front opening universal pods (FOUPs) 150 a,b. The process chambers130 a-d and the load lock chambers 120 a, 120 b are coupled to thetransfer chamber 110. The load lock chambers 120 a, 120 b areadditionally coupled to the FI 140. The FI 140 accepts the FOUPS 150 a,bcoupled thereto opposite the load lock chambers 120 a, 120 b. The loadlock chambers 120 a, 120 b include cassettes 135 disposed therein, whichare used to store substrates between processing operations. The transferchamber 110 includes a transfer robot 115 disposed therein. The transferrobot 115 is used to transfer substrates between the process chambers130 a-d and the load lock chambers 120 a, 120 b.

Each of the process chambers 130 a-d includes a loading port 125disposed adjacent to the transfer chamber 110 through which substratesenter or leave the process chambers 130 a-d. The process chambers 130a-d are described in greater detail in FIG. 2. In some embodiments thereare four process chambers 130 a-d, such that there is a first processingchamber 130 a, a second processing chamber 130 b, a third processingchamber 130 c, and a fourth processing chamber 130 d. The transferchamber 110 is a central chamber, which is configured to transfersubstrates within a controlled environment. The transfer chamber 110 ismaintained at a constant temperature and pressure. The transfer chamber110 may be vacuum isolated from each the process chambers 130 a-d whilesubstrates are being processed within the process chambers 130 a-d.

The load lock chambers 120 a, 120 b include a first load lock chamber120 a, and a second load lock chamber 120 b. The load lock chambers 120a, 120 b are disposed between and coupled to both the transfer chamber110 and the FI 140. Each of the load lock chambers 120 a, 120 b includea cassette 135. The cassette 135 is shown in greater detail in FIG. 3and described herein. The cassette 135 holds a plurality of substrates.The substrates are stored in the cassette 135 between processingoperations and may be moved by the transfer robot 115.

The FI 140 includes one or more robots (not shown) disposed therein.Substrates are transferred within the FI 140 between the FOUPs 150 a,band the load lock chambers 120 a, 120 b. The FI 140 is a cleanenvironment and may be held at a constant temperature and pressuredifferent from the transfer chamber 110.

The FOUPs 150 a,b include a first FOUP 150 a, and a second FOUP 150 b.There may be additional FOUPs not shown. The FOUPs 150 a,b are used forstoring substrates either before or after processing within the processchambers 130 a-d.

FIG. 2 is a schematic sectional view of a process chamber 130 a, whichincludes a measurement assembly 270 described herein, according to oneembodiment. The process chamber 130 a is the first process chamber, butthe second process chamber 130 b, the third process chamber 130 c, andthe fourth process chamber 130 d may be similar or the same as the firstprocess chamber 130 a. The process chamber 130 a may be used as anepitaxial deposition chamber, a rapid thermal process chamber, or otherthermal treatment chamber. The process chamber 130 a may be used toprocess one or more substrates, including the deposition of a materialon an upper surface of a substrate 202, heating of a substrate 202,etching of a substrate 202, or combinations thereof. The substrate 202is a device substrate and includes a plurality of partially formedsemiconductor devices formed thereon. The substrate 202 may be similarto a calibration substrate 350, which is used in place of the substrate202.

The process chamber 130 a generally includes a chamber body 248, anarray of radiant heating lamps 204 for heating, and a susceptor 206disposed within the process chamber 130 a. As shown in FIG. 2, an arrayof radiant heating lamps 204 may be disposed below the susceptor 206,above the susceptor 206, or both above and below the susceptor 206. Theradiant heating lamps 204 may provide a total lamp power of betweenabout 2 KW and about 150 KW. The radiant heating lamps 204 may heat thesubstrate 202 to a temperature of between about 350 degrees Celsius andabout 1150 degrees Celsius. The susceptor 206 may be a disk-likesubstrate support as shown, or may include a ring-like substrate support(not shown), which supports the substrate from the edge of thesubstrate, which exposes a backside of the substrate 202 to heat fromthe radiant heating lamps 204. The susceptor 206 may be formed fromsilicon carbide or graphite coated with silicon carbide to absorbradiant energy from the lamps 204 and conduct the radiant energy to thesubstrate 202, thus heating the substrate 202. In some embodiments, thesusceptor 206 serves as a radiation source after being heated to anelevated temperature. In such an example, the susceptor 206 serves as abroad-band radiation source and emits a broad range of wavelengths. Thesusceptor 206 may be at a temperature greater than 350° C., such asbetween about 350° C. and about 1200° C.

The susceptor 206 is located within the process chamber 130 a between afirst transmission member 208, which may be a dome, and a secondtransmission member 210, which may be a dome. The first transmissionmember 208 and the second transmission member 210, along with a basering 212 that is disposed between the first transmission member 208 andsecond transmission member 210, generally define an internal region 211of the process chamber 130 a. Each of the first transmission member 208and/or the second transmission member 210 may be convex and/or concaveand/or planar. In some embodiments, each of the first transmissionmember 208 and/or the second transmission member 210 are transparent.The first transmission member 208 is disposed between the chamber lid254 and the susceptor 206. In some embodiments, an array of radiantheating lamps 204 may be disposed outside of the internal region 211 ofthe process chamber 130 a and/or above the first transmission member208, for example, a region 201 defined between the first transmissionmember 208 and a chamber lid 254). The substrate 202 can be transferredinto the process chamber 130 a and positioned onto the susceptor 206through a loading port 125 formed in the base ring 212. A process gasinlet 214 and a gas outlet 216 are provided in the base ring 212.

The susceptor 206 includes a shaft or stem 218 that is coupled to amotion assembly 220. The motion assembly 220 includes one or moreactuators and/or adjustment devices that provide movement and/oradjustment of the stem 218 and/or the susceptor 206 within the internalregion 211. For example, the motion assembly 220 may include a rotaryactuator 222 that rotates the susceptor 206 about a longitudinal axis Aof the process chamber 130 a. The longitudinal axis A may include acenter of an X-Y plane of the process chamber 130 a. The motion assembly220 may include a vertical actuator 224 to lift and lower the susceptor206 in the Z direction. The motion assembly 220 may include a tiltadjustment device 226 that is used to adjust a planar orientation of thesusceptor 206 in the internal region 211. The motion assembly 220 mayalso include a lateral adjustment device 228 that is utilized to adjustthe positioning of the stem 218 and/or the susceptor 206 side to sidewithin the internal region 211. In embodiments including a lateraladjustment device 228 and a tilt adjustment device 226, the lateraladjustment device 228 is utilized to adjust positioning of the stem 218and/or the susceptor 206 in the X and/or Y direction while the tiltadjustment device 226 adjusts an angular orientation (a) of the stem 218and/or the susceptor 206. In one embodiment, the motion assembly 220includes a pivot mechanism 230. As the second transmission member 210 isattached to the process chamber 130 a by the base ring 212, the pivotmechanism 230 is utilized to allow the motion assembly 220 to move thestem 218 and/or the susceptor 206 at least in the angular orientation(a) to reduce stresses on the second transmission member 210.

The susceptor 206 is shown in an elevated processing position but may belifted or lowered vertically by the motion assembly 220 as describedabove. The susceptor 206 may be lowered to a transfer position (belowthe processing position) to allow lift pins 232 to contact the secondtransmission member 210. The lift pins 232 extend through holes 207 inthe susceptor 206 as the susceptor 206 is lowered, and the lift pins 232raise the substrate 202 from the susceptor 206. A robot, such as therobot 115, may then enter the process chamber 130 a to engage and removethe substrate therefrom though the loading port 125. A new substrate 202may be loaded onto the lift pins 232 by the robot, and the susceptor 206may then be actuated up to the processing position to place thesubstrate 202, with its device side 258 facing up. The lift pins 232include an enlarged head allowing the lift pins 232 to be suspended inopenings by the susceptor 206 in the processing position. In oneembodiment, stand-offs 234 coupled to the second transmission member 210are utilized to provide a flat surface for the lift pins 232 to contact.The stand-offs provide one or more surfaces parallel to the X-Y plane ofthe process chamber 130 a and may be used to prevent binding of the liftpins 232 that may occur if the end thereof is allowed to contact thecurved surface of the second transmission member 210. The stand-offs 234may be made of an optically transparent material, such as quartz, toallow energy from the lamps 204 to pass therethrough.

The susceptor 206, while located in the processing position, divides theinternal volume of the process chamber 130 a into a process gas region236 that is above the susceptor 206, and a purge gas region 238 belowthe susceptor 206. The susceptor 206 is rotated during processing by therotary actuator 222 to minimize the effect of thermal and process gasflow spatial anomalies within the process chamber 130 a and thusfacilitates uniform processing of the substrate 202. The susceptor 206may rotate at between about 5 RPM and about 100 RPM, for example,between about 10 RPM and about 50 RPM. The susceptor 206 is supported bythe stem 218, which is generally centered on the susceptor 206 andfacilitates movement of the susceptor 206 substrate 202 in a verticaldirection (Z direction) during substrate transfer, and in someinstances, processing of the substrate 202.

In general, the central portion of the first transmission member 208 andthe central portion of the second transmission member 210 are formedfrom an optically transparent material such as quartz. The thickness andthe degree of curvature of the first transmission member 208 may beselected to provide a flatter geometry for uniform flow in the processchamber.

One or more lamps, such as an array of the radiant heating lamps 204,can be disposed adjacent to and beneath the second transmission member210 in a specified manner around the stem 218. The radiant heating lamps204 may be independently controlled in zones in order to control thetemperature of various regions of the substrate 202 as the process gaspasses thereover, thus facilitating the deposition of a material ontothe upper surface of the substrate 202. While not discussed here indetail, the deposited material may include silicon, doped silicon,germanium, doped germanium, silicon germanium, doped silicon germanium,gallium arsenide, gallium nitride, or aluminum gallium nitride.

The radiant heating lamps 204 may include a radiant heat source,depicted here as a lamp bulb 241, and may be configured to heat thesubstrate 202 to a temperature within a range of about 200 degreesCelsius to about 1,600 degrees Celsius. Each lamp bulb 241 can becoupled to a controller 250. The controller 250 includes powerdistribution board, such as printed circuit board (PCB) 252, memory 255,and support circuits 257. The controller 250 may supply power to eachlamp bulb 241, control the process gas source 251, control the purge gassource 262, control the vacuum pump 257, and control the measurementassembly 270. A standoff may be used to couple the lamp bulb 241 to thepower distribution board, if desired, to change the arrangement oflamps. In one embodiment, the radiant heating lamps 204 are positionedwithin a lamphead 245 which may be cooled during or after processing by,for example, a cooling fluid introduced into channels 249 locatedbetween the radiant heating lamps 204.

In some embodiments, a liner 263 is disposed within the base ring 212and surrounding the susceptor 206. The liner 263 is coupled to the basering 212 and protects the inside surface of the base ring 212 duringsubstrate processing. The process gas inlet 214, the gas outlet 216, andthe purge gas inlet 264 are all disposed through the liner 263. In someembodiments, the liner 263 is a reflective liner.

Process gas supplied from a process gas supply source 251 is introducedinto the process gas region 236 through the process gas inlet 214 formedin the sidewall of the base ring 212. The process gas inlet 214 isconfigured to direct the process gas in a generally radially inwarddirection. As such, in some embodiments, the process gas inlet 214 maybe a cross-flow gas injector. The cross-flow gas injector is positionedto direct the process gas across a surface of the susceptor 206 and/orthe substrate 202. During a film formation process, the susceptor 206 islocated in the processing position, which is adjacent to and at aboutthe same elevation as the process gas inlet 214, thus allowing theprocess gas to flow generally across the upper surface of the susceptor206 and/or substrate 202. The process gas exits the process gas region236 through the gas outlet 216 located on the opposite side of theprocess chamber 130 a as the process gas inlet 214. Removal of theprocess gas through the gas outlet 216 may be facilitated by a vacuumpump 257 coupled thereto. In some embodiments, there are multipleprocess gas inlets 214 and multiple gas outlets 216. In someembodiments, there are five or more process gas inlets 214 disposedalong the inner circumference of the base ring 212 and three or more gasoutlets 216 disposed along the inner circumference of the base ring 212.Each of the process gas inlets 214 and the gas outlets 216 are parallelto one another and are configured to direct or receive process gas whichflows along different portions of the substrate 202.

Purge gas supplied from a purge gas source 262 is introduced to thepurge gas region 238 through the purge gas inlet 264 formed in thesidewall of the base ring 212. The purge gas inlet 264 is disposed at anelevation below the process gas inlet 214. The purge gas inlet 264 isconfigured to direct the purge gas in a generally radially inwarddirection. The purge gas inlet 264 may be configured to direct the purgegas in an upward direction. During a film formation process, thesusceptor 206 is located at a position such that the purge gas flowsgenerally across a back side of the susceptor 206. The purge gas exitsthe purge gas region 238 and is exhausted out of the process chamber 130a through the gas outlet 216 located on the opposite side of the processchamber 130 a as the purge gas inlet 264.

The measurement assembly 270 enables accurate measurement of thetemperature of the substrate 202. Substrate temperature is measured bynon-contact temperature sensors 272, 278 configured to measuretemperature at the device side 258 of the substrate 202 and the bottomside 253 of the substrate 202. The measurement assembly 270 furtherincludes light source 274 and the band edge detector 276. Each of afirst non-contact temperature sensor 272, the light source 274, and theband edge detector 276 are disposed above the substrate 202. A secondnon-contact temperature sensor 278 is disposed below the substrate 202and within the lamphead 245. The non-contact temperature sensors 272,278 may be pyrometers disposed in ports formed in the chamber lid 254 orthe lamphead 245.

The light source 274 is a laser light source with a controlled intensityand wavelength range. In some embodiments, a broad band light source isutilized. The light source 274 may be a diode laser or an optical cable.When the light source 274 is an optical cable, the optical cable isconnected to an independent light source, which may be disposed near theprocess chamber. The light source 274 may alternatively be a bundle oflasers or optical cables, such that a plurality of light beams arefocused into a first calibration light beam 286. In some embodiments,the light source 274 can emit radiation at a varying wavelength range.The varying wavelength range allows the light source 274 to emitwavelengths which would be within about 200 nm of the expectedabsorption edge wavelength of the calibration substrate. The use of avarying wavelength range eliminates noise which may be caused by the useof a wider wavelength spectrum and allows for an increase in thestrength of emission of the narrower range from the light source 274 toincrease the signal strength received by the band edge detector 276. Insome embodiments, one or more of the radiant heating lamps 204 areutilized as the light source 274, and the light source 274 is disposedbetween the chamber lid 254 and the first transmission member 208. Insome embodiments, the light source 274 may be classified as a radiationsource, such as a thermal radiation source or a broad band radiationsource. The radiation source may be a laser diode or an opticalassembly. The optical assembly may include a laser, a lamp, or a bulb aswell as a plurality of lenses, mirrors, or a combination of lenses andmirrors.

The band edge detector 276 measures the intensity of differentwavelengths of light within a second calibration light beam 284, whichis reflected off the calibration substrate 350. The band edge detector276 is configured to find a wavelength at which the calibrationsubstrate 350 transitions from absorbing a wavelength of radiation toreflecting nearly all of a wavelength of radiation. The band edgedetector 276 may include several optical components disposed therein inorder to separate and measure the second calibration light beam 284. Insome embodiments, the band edge detector 276 is a scanning band edgedetector and scans through a range of wavelengths to determine thetransition wavelength at which the calibration substrate 350 transitionsfrom absorbing to reflecting radiation. In some embodiments, the bandedge detector 276 measures the intensity of wavelengths of lighttransmitted through a calibration substrate 350 (described below) fromthe susceptor 206. As described above, in some instances the susceptor206 serves as a radiation source. The intensity of wavelengths of theradiation emitted by the susceptor 206 and transmitted through thecalibrations substrate 350 or a substrate 202 may be measured by theband edge detector 276. The band edge detector 276 then determines awavelength at which the calibration substrate 350 transitions fromabsorbing wavelengths to transmitting wavelengths. An optional filtermay be placed between the band edge detector 276 and the susceptor andconfigured to filter out radiation emitted by the lamp bulbs 241.

In some embodiments, a second band edge detector is disposed below thesusceptor 206. The second band edge detector may be in a similarposition as the second non-contact temperature sensor 278 and/or mayreplace or be combined with the second non-contact temperature sensor278. The second band edge detector is similar in structure to the firstband edge detector 276, but calibrates the second non-contacttemperature sensor 278 by measuring the intensity of the wavelengthstransmitted through the calibration substrate 350 through a lower windowdisposed within the susceptor 206. The second non-contact temperaturesensor 278 and the second band edge detector are both represented hereinby the second non-contact temperature sensor 278, but it is generallyunderstood that the second band edge detector and the second non-contacttemperature sensor 28 may have a similar spatial relationship as thatshown between the band edge detector 276 and the first non-contacttemperature sensor 278.

During the calibration methods disclosed herein, the substrate 202 isreplaced with a calibration substrate 350. The calibration substrate 350is similar in size and shape as the substrate 202. The calibrationsubstrate 350 includes a top side 358 and a bottom side 353. The topside 358 is similar to the device side 258 of the substrate 202 and thebottom side 353 is similar to the bottom side 253 of the substrate 202.The calibration substrate 350 may be made of a variety of crystalstructure materials. Exemplary materials and compounds which may formthe calibration substrate 350 include Si, Ge, SiC, GaN, GaAs, AlN, InN,3C—SiC, or InP material. Different materials with different crystalstructures are known to have different band gaps with differenttemperature ranges. In embodiments described herein, a calibrationsubstrate 350 formed from a crystalline SiC material is beneficial asthe crystalline SiC material has an absorption edge wavelength which iseasily measured using current band edge detection technology fortemperatures between about 300° C. and about 1200° C. The band gap canbe measured by determining the wavelength at which radiation transitionsfrom being absorbed by the material to reflected by the material.

The calibration substrate 350 is formed from a single material orcompound, as introducing additional materials/compounds may causemultiple band gaps to be measured by the band edge detector 276. In someembodiments, the calibration substrate 350 has a concentration of asingle compound or material greater than about 95%, such as greater than98%, such as greater than 99%, such as greater than 99.9%, such asgreater than 99.99%, such as greater than 99.999%. The calibrationsubstrate 350 is a crystalline material and non-crystalline material isminimized to improve band gap edge detection. Using a calibrationwavelength with a high percentage of a single material also increasesthermal uniformity within the calibration substrate 350. Thermaluniformity improved the accuracy of a comparison between the temperaturemeasurements of the first and second non-contact temperature sensors272, 278 and the band edge detector 276 when each of the measuredtemperatures are from slightly different positions along the surface ofthe calibration substrate 350.

During calibration of the first and second non-contact temperaturesensors 272, 278, a first measurement radiation path 282 of the firstnon-contact temperature sensor 272 is disposed between the firstnon-contact temperature sensor 272 and the device side 358 of thecalibration substrate 350. A second measurement radiation path 288 ofthe second non-contact temperature sensor 278 is disposed between thesecond non-contact temperature sensor 278 and the bottom side 353 of thecalibration substrate 350. The first calibration light beam 286 isemitted by the light source 274 and strikes the top side 358 of thecalibration substrate 350 before being reflected as the secondcalibration light beam 284 and received by the band edge detector 276.The band edge detector 276 analyzes the wavelengths of the secondcalibration light beam 284 and determines an actual temperature of thecalibration substrate 350. The method in which the actual temperature ofthe calibration substrate 350 is determined is described herein (FIGS. 5and 6). The actual temperature of the calibration substrate 350 iscompared to the temperatures measured by the first and secondnon-contact temperature sensors 272, 278 to facilitate calibration ofthe first and second non-contact temperature sensors 272, 278.

The chamber lid 254 may be a reflector and optionally placed outside thefirst transmission member 208 to reflect infrared (IR) light that isradiating off the substrate 202 and redirect the energy back onto thesubstrate 202. The chamber lid 254 may be secured above the firsttransmission member 208 using a clamp ring 256. The chamber lid 254 canbe made of a metal such as aluminum or stainless steel. The measurementassembly 270 is disposed through the chamber lid 254 to receiveradiation from the device side 250 of the substrate 202.

FIG. 3 is a schematic side view of a cassette 135 used within a loadlock chamber 120 a, 120 b of the substrate processing system 100 of FIG.1, according to one embodiment. The cassette 135 is used to storesubstrates, such as the substrates 202 while the substrates are notbeing processed within the process chambers 130 a-d. The cassette 135includes an upper member 304, a lower member 302, and a plurality ofsupport members 306.

The upper member 304 and the lower member 302 are disk shaped and havethe same diameter. The diameters of the upper member 304 and the lowermember 302 are about 305 mm to about 325 mm when a 300 mm substrate isstored within the cassette 135. The diameters of the upper member 304and the lower member 302 are about 10 mm to about 25 mm, such as about10 mm to about 15 mm larger than the outer diameter of the substrates202.

The plurality of support members 306 are vertically disposed andconfigured to hold substrates, such as the substrate 202, as well as thecalibration substrate 350. The support members 306 are disposed betweenthe upper member 304 and the lower member 302. The support members 306are coupled to each of the upper member 304 and the lower member 302.The support members 306 include a first support member 308, a secondsupport member 310, and a third support member 312. Each of the first,second, and third support members 308, 310, 312 include a plurality ofledges 320 disposed therein. The ledges 320 within each of the first,second, and third support members 308, 310, 312 face radially inwardtowards a central axis 325 of the cassette 135.

Each of the first, second, and third support members 308, 310, 312 have20 to 50 ledges, such as about 25 to 40 ledges for supportingsubstrates, such as substrate 202 and calibration substrate 350. In someembodiments, the cassette 135 has 28 ledges disposed in each of thefirst, second, and third support members 308, 310, 312, so that at leastone calibration substrate 350 can be stored within the cassette 135along with 25 device substrates 202. The substrates 202 and thecalibration substrate 350 are held in a horizontal position while storedin the cassette 135 and are contacted at an outer edge by the ledges 320from each of the first, second, and third support members 308, 310, 312.

FIG. 4 is a schematic sectional view of the measurement assembly 270used within the process chamber 130 a of FIG. 2, according to oneembodiment. In addition to the components described with regard to FIG.2, the measurement assembly 270 of FIG. 4 further includes a firstwindow 403, a second window 408, a third window 404, a fourth window407, and a cover 420.

The first window 403 is disposed within a first opening 402. The firstwindow 403 is disposed between the first non-contact temperature sensor272 and the first transmission member 208. Therefore, the first window403 is disposed between the first non-contact temperature sensor 272 andthe calibration substrate 350. The first window 403 is a quartz windowand allows for radiation from within the process chamber 130 a to passtherethrough. The first window 403 may filter radiation emitted by thecalibration substrate 350 to allow only wavelengths which the firstnon-contact temperature sensor 272 measures. The radiation travelingalong the first measurement radiation path 282 travels between the topside 358 of the calibration substrate 350 and the first non-contacttemperature sensor 272. The first measurement radiation path 282intersects both the first transmission member 208 and the first window403. In some embodiments, which may be combined with other embodiments,the first measurement radiation path 282 may intersect the top side 358of the calibration substrate 350 at any radial position along thecalibration substrate 350. In some embodiments, the first measurementradiation path 282 intersects the top side 358 of the calibrationsubstrate 350 at a specific location, such as either less than 15 mmfrom the center of the substrate, such as less than 10 mm from thecenter of the substrate, such as less than 5 mm from the center of thesubstrate or the first measurement radiation path 282 intersects the topside 258 of the calibration substrate 350 at a radius of about 110 mm toabout 130 mm, such as about 115 mm to about 125 mm, such as about 120mm.

The second window 408 is disposed within a second opening 409. Thesecond window 408 is disposed between the second non-contact temperaturesensor 278 and the second transmission member 210. Therefore, the secondwindow 408 is disposed between the second non-contact temperature sensor278 and the calibration substrate 350. The second window 408 is a quartzwindow and allows for radiation from within the process chamber 130 a topass there through. The second window 408 may filter radiation emittedby the calibration substrate 350 to allow only wavelengths which thesecond non-contact temperature sensor 278 measures. The radiationtraveling along the second measurement radiation path 288 travelsbetween the bottom side of the susceptor 206 and the second non-contacttemperature sensor 278. The second measurement radiation path 288intersects both the second transmission member 210 and the second window408. In some examples, the second measurement radiation path 288 mayintersect the bottom side of the susceptor 206 at any radial positionalong the calibration substrate 350. In other examples, the secondmeasurement radiation path 288 intersects the bottom side of thesusceptor 206 at a specific radial position, such as a radial positiondirectly below the calibration substrate 350 and either less than 15 mmfrom the center of the substrate, such as less than 10 mm from thecenter of the substrate, such as less than 5 mm from the center of thesubstrate or the second measurement radiation path 288 intersects thebottom side of the susceptor 206 at a radial position directly below thecalibration substrate 350 at a radius of about 110 mm to about 130 mm,such as about 115 mm to about 125 mm, such as about 120 mm.

The third window 404 is disposed within a third opening 405. The thirdwindow 404 is disposed between the light source 274 and the firsttransmission member 208. Therefore, the third window 404 is disposedbetween the light source 274 and the calibration substrate 350. Thethird window 404 allows light emitted by the light source 274 to passthere through. The light emitted by the light source 274 and travelingalong the first calibration light beam 286 is disposed between the lightsource 274 and the top side 358 of the calibration substrate 350. Thefirst calibration light beam 286 passes through both of the firsttransmission member 208 and the third window 404. The first calibrationlight beam 286 may intersect the top side 358 of the calibrationsubstrate 350 at any radial position along the calibration substrate350. In some examples, the first calibration light beam 286 intersectsthe top side 358 of the calibration substrate 350 either less than 15 mmfrom the center of the substrate, such as less than 10 mm from thecenter of the substrate, such as less than 5 mm from the center of thesubstrate or the first calibration light beam 286 intersects the topside 258 of the calibration substrate 350 at a radius of about 110 mm toabout 130 mm, such as about 115 mm to about 125 mm, such as about 120mm.

The first calibration light beam 286 intersects the top side 258 of thecalibration substrate 350 within less than 5 mm, such as less than 2 mm,such as less than 1 mm from the location in which the first measurementradiation path 282 intersects the radiation path. In some embodiments,the first calibration light beam 286 intersects the top side 258 of thecalibration substrate 350 at the same radial position as the firstmeasurement radiation path 282. Measuring the calibration substrate 350at the same location allows for a direct comparison between temperaturemeasurements and reduces error when compared to measurements made atdifferent radial distances from the center of the calibration substrate350.

The fourth window 407 is disposed within a fourth opening 406 formedthrough the chamber lid 254. The fourth window 407 is disposed betweenthe band edge detector 276 and the first transmission member 208.Therefore, the fourth window 407 is also disposed between the band edgedetector 276 and the calibration substrate 350.

The light received by the band edge detector 276 and traveling along thesecond calibration light beam 284 is disposed between the band edgedetector 276 and the top side 358 of the calibration substrate 350. Thesecond calibration light beam 284 passes through both of the firsttransmission member 208 and the fourth window 407. The secondcalibration light beam 284 intersects the top side 358 of thecalibration substrate 350 at the same location as the first calibrationlight beam 286. The second calibration light beam 284 is a reflection ofthe first calibration light beam 286 off the top side 258 of thecalibration substrate 350. The second calibration light beam 286 isaltered by intersecting the calibration substrate 350 and has a reducedwavelength range that is measured by the band edge detector 276.

The cover 420 is disposed above the chamber lid 254 and surrounds thefirst non-contact temperature sensor 272, the light source 274, and theband edge detector 276. The cover 420 may alternatively be disposedaround each of the first non-contact temperature sensor 272, the lightsource 274, and the band edge detector 276 individually, such that thereare a plurality of covers 420. The cover 420 may serve as a support tohold each of the first non-contact temperature sensor 272, the lightsource 274, and the band edge detector 276 in place. The cover 420prevents radiant energy from escaping the process chamber 130 a andinterfering with other equipment.

The temperature of a portion of the susceptor 206 is measured using thesecond non-contact temperature sensor 278. The temperature of a portionof the susceptor 206 measured using the second non-contact temperaturesensor 278 is a bottom surface and disposed opposite the location atwhich the calibration substrate 350 is measured by the first non-contacttemperature sensor.

FIG. 5 is a method 500 of utilizing the measurement assembly 270 withinthe process chamber 130 a of FIG. 2, according to one embodiment. Themethod 500 includes a first operation 502, a second operation 504, athird operation 506, a fourth operation 508, a fifth operation 510, asixth operation 512, and a seventh operation 514. Each of the operations502, 504, 506, 508, 510, 512, and 514 are performed sequentially asshown in FIG. 5 and described herein.

The method 500 includes a first operation 502 of transferring acalibration substrate, such as the calibration substrate 350 from acassette, such as the cassette 135 (FIG. 3). The calibration substrate350 is stored within the cassette between each calibration of the firstand second non-contact temperature sensors 272, 278 (FIG. 4). Thecalibration substrate 350 is removed from the cassette by the transferrobot 115 within the transfer chamber 110 (FIG. 1).

During the second operation 504, the transfer robot transfers thecalibration substrate into the processing chamber, such as theprocessing chamber 130 a or any of the other processing chambers 130 b,130 c, 130 d (FIGS. 1 and 2). The calibration substrate passes throughthe transfer chamber 110 before being inserted into the processingchamber through a loading port, such as the loading port 125 (FIG. 2).The calibration substrate is placed onto a susceptor and the transferrobot is retracted from the process chamber.

During the third operation 506, a calibration process is performed. Thecalibration process includes utilizing the calibration substrate and themeasurement assembly 270. The calibration process of the third operation506 is described in greater detail with reference to the method 600 ofcalibrating the non-contact temperature sensors.

After the third operation 506, the temperature calibration process isstopped in a fourth operation 508. Stopping the temperature calibrationprocess includes stopping the flow of any process gases introduced intothe process chamber, stopping of any heating of the calibrationsubstrate, and ceasing of the measurement of the temperature of thecalibration substrate.

After the temperature calibration process is ceased, the calibrationsubstrate is removed from the process chamber during a fifth operation510. The calibration substrate is removed by the transfer robot throughthe loading port. The calibration substrate is inserted back into thecassette subsequent to being removed from the process chamber.

After removal of the calibration substrate from the process chamber, asemiconductor substrate may be transferred into the process chamberduring the sixth operation 512. The semiconductor substrate may besimilar to the substrate 202 (FIG. 1). The semiconductor substrate mayhave partially formed semiconductor devices disposed thereon. Thesemiconductor substrate is transferred into the process chamber by thetransfer robot and may have been stored within the cassette during thetemperature calibration process or may have been stored in a separateprocess chamber.

Subsequent to the sixth operation 512 of transferring a semiconductorsubstrate into the process chamber, a substrate processing operation isperformed during the seventh operation 514. The substrate processingoperation may include a deposition process on the top surface of thesubstrate. The substrate processing operation may further includeheating the substrate, introducing at least one process gas, introducinga purge gas, and evacuating the process and purge gases. A plurality ofsubstrates are processed during the substrate processing operation.

The sixth and seventh operations 512, 514 are repeated so that betweeneach calibration process multiple substrates are processed. The sixthand seventh operations 512, 514 may be repeated, such that more than 50substrates are processed within the processing chamber between eachcalibration process. In some embodiments, the calibration process isonly performed once every several days and several hundred substratesare processed within the processing chamber between each calibrationprocess.

The method 500 is repeated automatically after a preset amount ofsubstrates have been processed within the processing chamber or afterthe processing chamber has reached a preset run time. The method 500 isautomated and programmed into a controller, such as the controller 250.The method 500 does not use human intervention and is completed withoutdisassembly of the process chambers. The calibration of the non-contacttemperature sensors using the method 500 requires minimum downtime ofthe system by only pausing processing operations for the length of timeit takes to perform operations 504, 506, 508, and 510.

FIG. 6 is a method 600 of calibrating non-contact temperature sensors,such as the non-contact temperature sensors 272, 278, within the processchamber of FIG. 2, according to one embodiment. The method 600 is partof the third operation 506 of the method 500 described herein.Calibrating the non-contact temperature sensors includes a firstoperation 602, a second operation 604, a third operation 606, a fourthoperation 608, and a fifth operation 610. The operations 602, 604, 606,608, 610 described with regard to the method 600 are performedsubsequently as shown in FIG. 6 and described herein.

The first operation 602 includes performing a calibration processingoperation. The calibration processing operation may be similar to thesubstrate processing operation 514 performed on the regular substrate.The calibration processing operation includes heating the substrate,introducing a process gas, introducing a purge gas, and evacuating theprocess and purge gases. The process gas may be different from theprocess gas utilized in the substrate processing operation of theseventh operation 514 of the method 500. A process gas may be a carriergas, such as a H₂ gas. The carrier gas assists in matching processconditions with those found in the substrate processing operation 514.The carrier gas assists in matching the pressure and gas flow whichwould be found during the substrate processing operation 514. However,the process gas does not include reactant gases or deposition/etchgases, which may alter the surface of the calibration wafer. The processchamber and calibration substrate may be heated using the radiantheating lamps 204 (FIG. 2) and/or a susceptor heater (not shown). Theheating of the process chamber and the calibration substrate isperformed gradually and the temperature increases over time.

The second operation 604 includes measuring a wavelength of absorptionof the calibration substrate using the band edge detector 276 (FIG. 4).During the second operation 604 a first calibration light beam 286 isemitted by the light source 274 or one of the radiant heating lamps 204.When the first calibration light beam 286 strikes the top side 358 ofthe calibration substrate 350 at a first location, a first wavelengthrange of the first calibration light beam 286 is absorbed by thecalibration substrate 350 while a second wavelength range of the firstcalibration light beam 286 is reflected as the second calibration lightbeam 284. The second calibration light beam 284 enters the band edgedetector 276. The band edge detector 276 measures the intensity of avariety of wavelengths within the wavelength spectrum of the secondcalibration light beam 284. The band edge detector 276 maps theintensity of the wavelength measurements over the wavelength rangemeasured by the band edge detector 276. Either a broad band lightsource, such as the light source 274 is utilized to form the firstcalibration light beam 286, or one or more radiant heating lamps 204 isused to form the first calibration light beam 286. The light source 274may be beneficially utilized in order to improve the accuracy of themeasurement. The light source 274 may emit a precise range ofwavelengths at a set intensity and direction. This makes the lightsource 274 highly adjustable and may provide for improved measurementprecision. The radiant heating lamps 204 may be used to reduce thenumber of components disposed on a lid of the process chamber. Theradiant heating lamps 204 emit a range of light which may be similar tothe range emitted by the light source 274. The radiant heating lamps 204have a controlled intensity. The radiant heating lamps 204 may be usedto emit light which is absorbed and reflected by the calibrationsubstrate 350.

In some embodiments, which may be combined with other embodiments,radiation is transmitted through the calibration substrate and measuredby the band edge detector 276 on the opposite side of the calibrationsubstrate 350 from the radiation light source. This may occur when asusceptor on which the calibration substrate 350 is disposed istransparent to the light emitted by the light source at a wavelengthdetected by the band edge detector 276 or when the susceptor itselfemits radiation after heating.

The band edge detector 276 may measure the intensity of wavelengthsbetween about 250 nanometers (nm) to about 1350 nm, such as about 300 nmto about 1300 nm. The light sources (either the light source 274 or theradiant heating lamps 204) may emit light at a wavelength of about 250nm to about 1350 nm, such as about 300 nm to about 1300 nm.

An exemplary map of the intensity of the wavelength measurements iffound in FIG. 7. FIG. 7 shows the measurement of the intensity 708 ofwavelengths over a range of wavelengths 706. The range of wavelengths706 measured by the band edge detector 276 may be the same range ofwavelengths emitted by the light source 274 as the first calibrationlight beam 286. The intensity 708 of the wavelengths over the range ofwavelengths 706 is mapped to form an intensity curve 702. The intensitycurve 702 shows a sharp change between the wavelength range which isabsorbed by the calibration substrate 350, the wavelength range having alow or near zero measured intensity, and the wavelength range which isreflected by the calibration substrate 350, the wavelength range havinga high or near 1 measured intensity. The intensity is measured as afraction of the intensity of the wavelength emitted by the light source274. The absorption edge wavelength is disposed in the midpoint 704 ofthe transition between low measured intensity and high measuredintensity of the wavelength range. The absorption edge wavelength is thewavelength at which the wavelengths transition from being absorbed tobeing reflected by a material. The absorption edge wavelength isdirectly correlated to the band gap of a material and the band gap of amaterial is dependent upon the temperature of the material. Astemperature changes within an object, such as the calibration substrate350, the band gap and thus the absorption edge wavelength also changes.Therefore, a temperature of a material can be measured by measuring theabsorption edge wavelength.

Returning to FIG. 6, in the third operation 606, the band edge detector276 determines the temperature of the calibration substrate based off ofthe absorption edge wavelength found in the second operation 604. Agraph such as the correlated temperature graph 800 is utilized to equatethe absorption edge wavelength with a temperature. The correlation curve802 of the correlated temperature graph 800 may be found experimentallyand correlates temperature 806 to the measured absorption edgewavelength 804. The temperature determined by the band edge detector 276using the absorption edge wavelength is beneficial in that thedetermined temperature is not influenced by the aging of any componentswithin the process chamber, such as the process chamber 130 a of FIG. 2.The absorption edge wavelength is dependent upon temperature and thematerial of the calibration substrate 350, but is minimally influencedby the state of the components within the process chamber. Therefore,since the same calibration substrate 350 is utilized and stored betweeneach of the calibration processes, an accurate and repeatable actualtemperature is able to be performed using the measurement assembly 270and the band edge detector 276. The actual temperature is thetemperature measured by the band edge detector 276.

In the fourth operation 608 the temperature of the calibration substrate350 is determined using the first and second non-contact temperaturesensors described herein. The temperature of the first and secondnon-contact temperature sensors is determined by measuring the radiationemitted by the calibration substrate 350. In some embodiments, thenon-contact temperature sensors are pyrometers. The temperature measuredby the first non-contact temperature sensor is a first temperature, or afirst measured temperature. The temperature measured by the secondnon-contact temperature sensor is a second temperature, or a secondmeasured temperature. The areas of the calibration substrate 350 whichare measured by the first and second non-contact temperature sensors arewithin about 5 mm of the radial position of the area measured by theband edge detector. In some embodiments, each of the first and secondnon-contact temperature sensors measure an area with the same radius asthe area measured by the band edge detector. In some embodiments, thearea is also called a measurement point.

In some embodiments, the second and fourth operations 604, 608 areperformed simultaneously to ensure the temperatures measured areequivalent. In some embodiments, all of the second, third, and fourthoperations 604, 606, and 608 are performed simultaneously.

Over time, the temperature measurements of the first and secondnon-contact temperature sensors drifts due to aging and wear ofcomponents within the process chamber. Therefore, the temperaturemeasurements of the non-contact temperature sensors should be calibratedperiodically. In the fifth operation 610, the non-contact temperaturesensors are calibrated using the actual temperature determined by theband edge detector. The non-contact temperature sensors may be adjustedto a temperature matching or near (within a predetermined degree ofaccuracy) the temperature measured by the band edge detector.

In some embodiments, the method 600 of calibrating non-contacttemperature sensors described herein is performed multiple times at avariety of temperatures so that the first and second non-contacttemperature sensors may be calibrated to a wide range of temperatures.In some embodiments an adjustment algorithm can determine an optimumcalibration amount for the non-contact temperature sensors after themethod 600 has been repeated over a range of calibration substratetemperatures. The non-contact temperature sensors may be calibrated byadjusting each measurement by the same amount, or the non-contacttemperature sensors may be adjusted on a curve determined by thecontroller.

The embodiments disclosed herein relate to the calibration ofnon-contact temperature sensors within a thermal processing chamber,such as an epitaxial processing chamber, using a band edge detector andabsorption edge wavelengths. A calibration substrate is utilized tobetter enable consistent calibration results and provide an expectedabsorption edge wavelength for the material from which the calibrationsubstrate is formed.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

What is claimed is:
 1. A measurement assembly for calibrating at leastone pyrometer within a processing chamber comprising: a band edgecalibration assembly comprising: a light source positioned to emit alight and to irradiate a portion of a calibration substrate positionedon a substrate support within a chamber body of the processing chamber;and a band edge detector disposed adjacent to the light source andpositioned to receive the light emitted by the light source; a firstpyrometer disposed adjacent to the band edge calibration assembly andpositioned to receive radiation; and a controller configured to:determine a band edge absorption wavelength from the light received bythe band edge detector; determine an actual temperature of thecalibration substrate using the determined band edge absorptionwavelength; determine a first measured temperature of the calibrationsubstrate based on the received radiation of the first pyrometer; andcalibrate the first pyrometer by comparing the first measuredtemperature of the calibration substrate and the actual temperature ofthe calibration substrate.
 2. The measurement assembly of claim 1,wherein a cover is disposed around the light source and the band edgedetector.
 3. The measurement assembly of claim 1, wherein a first quartzwindow is disposed adjacent to the light source while a second quartzwindow is disposed adjacent to the first pyrometer.
 4. The measurementassembly of claim 1, wherein the band edge detector is a scanning bandedge detector.
 5. The measurement assembly of claim 4, wherein the bandedge detector is configured to measure an intensity of light over arange of wavelengths.
 6. The measurement assembly of claim 1, whereinthe light source is a broad band light source.
 7. The measurementassembly of claim 1, wherein the calibration substrate is disposed in alight path of the light, wherein the light is reflected off of thecalibration substrate before being received by the band edge detector.8. The measurement assembly of claim 7, further comprising a secondpyrometer disposed on an opposite side of the calibration substrate fromthe band edge calibration assembly and the first pyrometer.
 9. Anapparatus for substrate processing comprising: a chamber body; asubstrate support disposed within the chamber body; a first transmissionmember disposed over the substrate support and within the chamber body;a second transmission member disposed below the substrate support andwithin the chamber body; a lid disposed above the first transmissionmember; a plurality of lamps disposed between the first transmissionmember and the lid; a calibration substrate disposed on the substratesupport; a radiation source positioned to direct radiation onto orthrough the calibration substrate; a band edge calibration assemblydisposed on the lid comprising: a band edge detector positioned toreceive the radiation from the radiation source after being reflectedoff of or passing through the calibration substrate; a first pyrometerdisposed adjacent to the band edge calibration assembly; a transferchamber coupled to the chamber body; a load lock chamber coupled to thetransfer chamber, wherein the load lock chamber further comprises acassette for substrate storage; and a controller configured to:irradiate a portion of the calibration substrate using the radiationsource; measure a band edge absorption wavelength; measure a firsttemperature of the calibration substrate using the first pyrometer;determine an actual temperature of the calibration substrate using theband edge absorption wavelength; and calibrate the first pyrometer bycomparing the first temperature of the calibration substrate and theactual temperature of the calibration substrate.
 10. The apparatus ofclaim 9, wherein the calibration substrate is a Si, Ge, SiC, GaN, GaAs,AlN, InN, 3C—SiC, or InP material.
 11. The apparatus of claim 10,wherein the calibration substrate is a crystalline SiC material.
 12. Theapparatus of claim 9, further comprising a second pyrometer disposedbelow the substrate support.
 13. The apparatus of claim 9, wherein theradiation source is a light source disposed adjacent to the band edgedetector and a first window is between the light source and thecalibration substrate while a second window is disposed between to thefirst pyrometer and the calibration substrate.
 14. The apparatus ofclaim 9, wherein the plurality of lamps are infrared radiation lamps.15. A method of calibrating a pyrometer within a process chambercomprising: transferring a calibration substrate onto a substratesupport within a chamber body; irradiating a portion of the calibrationsubstrate using a light source; measuring a band edge absorptionwavelength using a band edge detector; measuring a first temperature ofthe calibration substrate using a first pyrometer; determining an actualtemperature of the calibration substrate using the band edge absorptionwavelength; calibrating the first pyrometer by comparing the firsttemperature of the calibration substrate and the actual temperature ofthe calibration substrate; and transferring the calibration substrateout of the chamber body.
 16. The method of claim 15, further comprisingperforming a substrate processing operation prior to the irradiating,the substrate processing operation comprising: heating the calibrationsubstrate with a plurality of lamps; and introducing a process gas intothe chamber body.
 17. The method of claim 15, wherein the measuring theband edge absorption wavelength comprises measures an intensity of avariety of wavelengths within a wavelength spectrum of a calibrationlight beam.
 18. The method of claim 15, wherein the calibrationsubstrate is stored in a cassette before being transferred into thechamber body and after transferring the calibration substrate out of thechamber body.
 19. The method of claim 18, wherein after transferring thecalibration substrate out of the chamber body, a plurality of substratesare processed within the chamber body.